Steel composition

Abstract

Chain parts and other steel articles are provided with hard, wear-resistant carbide coatings by tumbling them in a heated retort with a particulate mix which includes a source of vanadium and/or niobium. The steel substrate comprises a steel having at least 0.2% carbon, preferably 0.7-1.2%. Where the chromium content of the steel is 4-12%, preferably 4-8%, the chemical deposition process includes drawing a small amount of chromium from the steel substrate into the vanadium or niobium carbide coating, where it is distributed substantially homogeneously, helping to provide adhesion strength to the coating.

What is claimed is:  
     
       1. A layered steel composition comprising, in weight percent, (a) a core composition comprising: 
       
         
           
                 
                 
                 
                 
                 
                 
                 
                 
               
                     
                 
                   C 
                   Cr 
                   Mn 
                   Si 
                   Mo 
                   P 
                   S 
                   Al 
                 
                     
                 
                   0.7-1.2 
                   4-8 
                   0.25- 
                   0.25- 
                   0.2- 
                   0.03 max 
                   0.03 max 
                   0.05 max 
                 
                     
                     
                   0.45 
                   0.55 
                   0.55 
                 
                     
                 
             
                
                
                
               
               
                
                
                
               
            
           
         
       
       and (b) a coating composition thereon comprising 97-99% by weight carbide of at least one Group 5 metal having an atomic number no greater than 41. 
     
     
       2. A layered steel composition of  claim 1  wherein said coating composition includes 1-3% by weight chromium carbide. 
     
     
       3. A layered steel composition of  claim 1  wherein said Group 5 metal comprises vanadium. 
     
     
       4. A layered steel composition of  claim 1  wherein said Group 5 metal comprises niobium.